1. Field of the Invention
This invention is in the field of internal combustion engines and particularly the field of internal combustion engines burning solid fuels alone or in combination with liquid or gaseous fuels.
2. Description of the Prior Art
Relevant Prior Art is described in the following U.S. patents issued to applicant:
U.S. Pat. No. 4,372,256, Feb. 8, 1983 PA0 U.S. Pat. No. 4,412,511, Nov. 1, 1983 PA0 U.S. Pat. No. 4,698,069, Oct. 6, 1987 PA0 U.S. Pat. No. 4,794,729, Jan. 3, 1989
Char burning engines are described in these patents wherein char fuel, contained within a char fuel reaction chamber, is cyclically compressed with air followed by expansion of the product gases resulting from reaction of char fuel with compressed air. Most char fuels will react appreciably with the oxygen gas in the compressed air only when at a sufficiently high temperature, of the order of 900.degree. F. to 1000.degree. F. Most char fuels will react rapidly with the oxygen gas in the compressed air only when at a higher temperature, of the order of 1200.degree. F. to 1800.degree. F., thus to start such char burning engines requires heating char fuel within the char fuel reaction chamber, first to that temperature at which it will react appreciably with oxygen gas, and secondly to that higher temperature at which it will react rapidly with oxygen gas while the engine is being cranked for starting. The engine will be fully started only when a sufficient portion of the char fuel is at its rapid reaction temperature that the net work of the cycle of compression followed by expansion on char fuel alone at least equals the friction work of the internal combustion engine mechanism and the engine is then capable of cranking itself.
Various methods of starting a char burning engine are described in U.S. Pat. No. 4,412,511, column 4, line 65, through column 5, line 2, and column 35, line 36, through column 37, line 29, and this material is incorporated herein by reference thereto. Among other starting methods a diesel engine starting method is described wherein the engine is equipped to start as a conventional diesel engine. During the pressure rise caused by burning of the diesel fuel, hot oxygen will be forced into the pores of the char fuel to heat it up and eventually start the char burning rapidly. When the char is capable of rapid burning, the diesel fuel can be turned off and the engine then run on the char fuel. With this diesel engine starting method the liquid fuel is necessarily injected later during the engine compression process so that it can be compression ignited. As a result the time duration of flow of hot oxygen containing gas into the pores of the char fuel is short, being about equal to the time duration of diesel fuel combustion with pressure rise which is only a few degrees of crankshaft turning angle. Hence heatup of the char fuel is slow since only a portion of the gas compressed therein has been heated by diesel fuel combustion. As a result prolonged cranking is required before the char burning engine can be started running on char fuel. It would be desirable to have a char burning engine starting method which more quickly heated the char fuel to its rapid burning temperature.
Examples of char burning engines are described in general in U.S. Pat. No. 4,412,511, column 7, line 21 through column 11, line 45, and this material is incorporated herein by reference thereto. Such char burning engines comprise a char fuel reaction chamber into which char fuel is placed by a refuel mechanism via a refuel end and from which ashes are removed by an ash removal mechanism via an ash removal end and the char fuel reacts with oxygen in adjacent compressed gases within this char fuel reaction chamber.
The terms, internal combustion engine, and, internal combustion engine mechanism, are used herein and in the claims as defined in U.S. Pat. No. 4,412,511, column 1, line 65 through column 2, line 45, and this material is incorporated herein by reference thereto.
In some internal combustion engine mechanisms a reciprocating piston is operated within a cylinder as a combined means for compressing and expanding the gases, and the space enclosed by the piston crown and the cylinder walls is frequently also a reaction chamber wherein secondary reactions may occur during expansion. In this case the volume of this secondary reaction chamber varies cyclically and is a portion of the combined means for cyclically compressing and expanding gases. For multicylinder internal combustion mechanisms several combined means for compressing and expanding are joined together.
When such combined means for compressing and expanding the gases are used, each compression process occurs over a compression time interval during which the variable volume chamber decreases in volume and this is immediately followed by an expansion process occurring over an expansion time interval during which the variable volume chamber increases in volume.
For piston and cylinder mechanisms a crank and connecting rod, or equivalent mechanism, is used as a drive means for driving the internal combustion engine mechanism and the combined compressing and expanding means portion thereof through repeated cycles of compression followed by expansion. Various kinds of drive means and variable volume chamber means for compressing and expanding gases can be used such as the Wankel mechanism and the free piston mechanism as described, for example, in U.S. Pat. No. 4,372,256.
The term, oxygen gas, is used herein and in the claims as defined in U.S. Pat. No. 4,509,957, column 3, line 1 through line 8, and this material is incorporated herein by reference thereto.
The term, char fuel, is used herein and in the claims as defined in U.S. Pat. No. 4,412,511, column 2, line 46 through line 66, and this material is incorporated herein by reference thereto.
The term, changeable gas flow connection, is used herein and in the claims to means gas flow passages which can be opened or closed while the engine is running or being cranked for starting. The term, fixed open gas flow connection is used herein and in the claims to means gas flow passages which remain open whenever the engine is running or being cranked for starting.